The present invention relates to a moving body running on rails and a wheel thereof, and more specifically to a wheel for a moving body, which has a high coefficient of friction with steel rails and which also has high abrasion resistance.
Further, the present invention relates to a rail on which track-running moving body travels, and more particularly to a rail, which has a high coefficient of friction with a wheel and which also has high abrasion resistance.
As moving bodies that run on rails, there are vehicles that convey people and goods, working vehicles for changing the working position, and so on. Among the moving bodies, there are those that are equipped with driving wheels that receive driving power for self-propelled running on the rails. Generally, for the self-propelled moving bodies of this kind, to take an example, the locomotive has a tractive force, which is a product of the weight of the locomotive times the friction coefficient of the wheels.
Meanwhile, the rails and the moving bodies running on the rails, such as the wheels of the locomotive, are both generally made of steel. In this case, the friction coefficient between the wheel and the rail (hereafter sometimes referred to as xe2x80x9cxcexcxe2x80x9d) is 0.2 to less than 0.3. However, the friction coefficient to this level sometimes is not sufficient. For example, in a case of a moving body, such as a locomotive running on a steep grade, it is necessary to have a high tractive force to increase the gradability. However, there is a problem that the locomotive weight must increase over the necessity, since there is a limit at the size of friction coefficient between rail and wheel. On the other hand, for a moving body under a great load, because there is a large inertia, it takes time to accelerate, and a long braking distance is required in stopping.
For this, it is considered that the friction coefficient of the wheel""s tread, which contacts a rail, increases for increasing the friction coefficient between rail and wheel. It is possible to attach urethane rubber having xcexc of about 0.4, for example, to the tread of the wheel. However, when wheels fitted with urethane are used, there is a problem that the urethane rubber heats up and its service life is short.
Another possible way of increasing the friction coefficient is to change the material of the wheel itself. To take an example, it is possible to form a wheel of aluminum or an aluminum alloy. In such a case, the value of xcexc can be increased. Regrettably, those materials are low in abrasion resistance and short in life.
An object of the present invention is to provide a wheel for a track-running moving body, which has high abrasion resistance and high durability and which realizes a high coefficient of friction with the rails, and also provide a moving body equipped with the wheels mentioned above.
A second object of the present invention is to provide a rail, which has high abrasion resistance and high durability and which realizes a coefficient of friction with the wheels, and also provide a running installation using the rails mentioned above.
To achieve the first object, according to a first embodiment of the present invention, there is provided a wheel for a moving body running on rails, comprising a main body and a tread-forming component for forming a wheel tread attached to the outer circumference of the main body and being in contact with a rail, wherein the tread-forming component having at least in a portion thereof in contact with contacting the rail a ceramic-particle-dispersion reinforced aluminum-base composite material, which has ceramic particles mixed in an aluminum alloy.
As the above-mentioned material, one containing 5 to 25 vol % of ceramic particles, or preferably, one containing 10 to 20 vol % of ceramic particles is used.
The above-mentioned wheel for a moving body may include a fixing member for fixing the tread-forming component to the main body. In this case, the main body may be formed to have around the outer circumference thereof a tread-forming component receiving portion for accepting the tread-forming component, wherein the tread-forming component is inserted in the receiving portion and fixed to the main body by using the fixing member.
The main body may have around a circumference thereof a plurality of tapped holes bored in the axial direction on the bottom-face side of the tread-forming component receiving portion. The tread-forming component may have through-holes bored at positions corresponding to the tapped holes, and the tread-forming component can be fixed to the main body by screwing bolts into the tapped holes.
Further, according to a second embodiment of the present invention, there is provided a moving body having a driving mechanism to drive at least one of the wheels to run on the rails, wherein the wheel driven by the driving mechanism includes a main body and a tread-forming component for forming a tread that contacts the rail by being attached to the outer circumference of the main body, and wherein the tread-forming component has at least in a portion thereof in contact with the rail a ceramic-particle-dispersion reinforced aluminum-base composite material, which has ceramic particles mixed in an aluminum alloy.
As the above-mentioned material, one containing 5 to 25 vol % of ceramic particles, or preferably, one containing 10 to 20 vol % is used.
An example of the moving body is an electric rolling stock, which has wheels and a motor for driving at least a pair of wheels among the wheels and which runs on the rails. To achieve the second object of the present invention, according to a third embodiment of the present invention, there is provided a rail for supporting the running moving body, wherein the rail comprises a rail foot, a web part and a rail head, and wherein at that portion of the head rail which contacts at least the tread of a wheel, there is provided a member formed by a ceramic-particle-dispersion reinforced aluminum-base composite material, which has ceramic particles mixed in an aluminum alloy.
As the above-mentioned material, one containing 5 to 25 vol % of ceramic particles is preferably used.
The above-mentioned member formed by a ceramic-particle-dispersion reinforced aluminum-base composite material may be prepared separately from the rail head, and secured to the top face of the rail head.
Further, according to a fourth embodiment of the present invention, there is provided a moving body running installation in which rails according to the third embodiment are laid.
Further, according to a fifth embodiment of the present invention, a moving-body stoppage area is provided where rails according to the third embodiment are laid.
According to the present invention, a tread-forming component made of a ceramic-particle-dispersion reinforced aluminum-base composite material is used at the tread of a wheel that is in contact with a rail, and this makes it possible to provides a wheel with superior abrasion resistance and a high coefficient of friction with the rail.
In the preferred embodiments of the present invention, in at least either the wheel or the rail and at their contact area, a ceramic-particle-dispersion reinforced aluminum-base composite material is used, and this material contains 5 to 25 vol % of ceramic particles. More particularly, one containing 10 to 20 vol % of ceramic particles is preferably used. Accordingly, the friction coefficient between the rail steel and the wheel (tread-forming component) can be increased to about 0.8 to 0.9 in an experiment and to 0.4 to 0.45 in an experiment using test specimens in the shape of an actual wheel. Therefore, it becomes possible to increase the tractive force of the moving body on those wheels or improve the braking performance without increasing the weight of the moving body. For example, if rails made of materials mentioned above are laid in heavy-grade territories or stoppage areas, a short-distance braking can be realized without making a moving body with an especially large weight.
According to the present invention, it is possible to realize a wheel for a moving body, which has high abrasion resistance and high durability and which is provided with a high coefficient of friction with the rail, and also realize a moving body using such wheels. Furthermore, it is possible to realize rails with high abrasion resistance and high durability, and added with a high coefficient of friction with conventional steel wheels.